Making my dragon eggs louder and less crackles

[insutama]

ok perfect now just gotta wait for it to get here. what other comps is potassium dichromate used in ? anything with MG i take it ?

[lloyd]

Not every, but most compositions containing Magnesium (and to a significant degree fine Mg/Al) can benefit from using dichromate solution for the 'wetting water'. It helps eliminates the possibility of a 'runaway reaction' when wetting the comp.

 

Most older practices involved pre-treating the Mg with saturated dichromate solution, then drying and re-screening it. But over the years, we've determined that it's reliable to simply mix the uncoated Mg or Mg/Al into the composition, then use dichromate solution instead of water to wet the mixtures.

 

Lloyd

[insutama]

Thanks lloyd

[insutama]

I have made 100g of uniformed sized 10 mesh eggs i now want to prime them but my potassium dichromate is not here yet is there any other prime i can try for the meantime.

could i try using a alcohol redgum prime of green mix ? i know it will dissolve the eggs a bit but is it doable ?

[lloyd]

Straight alcohol solvent should not dissolve the NC lacquer in the DE. I'd try it.

 

Lloyd

[insutama]

okay so i just finished priming my eggs i used.

20 parts of BP meal powder

40 parts KN03

40 parts Silicon

+5% red gum

 

I put the eggs in a bowl then spritzed them with 99% iso alcohol then hand rolled the prime on the starts they look really nice at the moment just got a nice thin coat on them didnt change the size of the eggs much. there drying at the moment ill let you know the results.

[lloyd]

WTF, Insutama? You said 'green mix' (with red gum)!

 

I know dextrin-bound green mix works, so I presumed red gum-bound green mix would. But, instead of using what YOU said you would, you come up with some exotic mess that isn't necessary and might not work.

 

Why do you insist upon changing things before ever trying what's known to work, first?

 

Y'know, even if it works just fine, that's a dangerous strategy to use when trying a formula you're unfamiliar with.

 

I am a professional manufacturer of fireworks. I often try formulae I find published on the web or in books. Despite having 50 years' experience making fireworks and designing new formulae from 'scratch', I always follow the original author's instructions exactly when first trying a new formula. Otherwise, how can I possibly know if it works properly as-published?

 

Lloyd

Edited July 15, 2017 by lloyd

[insutama]

Well lloyd im waiting for my potassium dichromate so i can follow the formula however i had a bunch of nice sized eggs and no dichromate so i am just working with what i got for now and posting my results so others can learn from it and possible know if the future what works and what doesnt.

 

RESULTS:

 

The eggs were the best yet once primed very happy with results thanks for all your help now if only i could get USA pyros forumula to work as well.

Edited July 15, 2017 by insutama

[lloyd]

BS! I already told you that one of my compatriots coats the crackle without dichromate. I personally feel it's necessary, but it will work without it.

 

If you resort to changing all the rules, just because you don't have an optional substance, then you cheat yourself out of knowing if the material works as it should.

 

Lloyd

[insutama]

Well when my dichromate gets here i will be tring that method so i dont see it the same way you do lloyd im always gonna be trying new formulas out so i can find the best ones and not cheat myself out of knowing the best formulas and i didnt use water to prime my eggs i used iso alcohol 99% o thought it was a safer alternative than having my eggs spontaniously igniting

[Baldor]

Insutama, Lloyd have a point. If you go on wild tangent excursions from the known to work, before mastering the known to work methods, you are learning nothing, since you have nothing to compare to. You must try to follow the methods that are know to work, and if they doesn't work for you, you must investigate why they are not working. Most possible, the thing you are making wrong with one formula, you are making wrong in another places too. Then, when you have something to compare, you can start to experiment.

[lloyd]

"... i dont see it the same way you do lloyd im always gonna be trying new formulas out so i can find the best ones and not cheat myself out of knowing the best formulas..."

 

---------------

That's not the point, sir. You changed the process without knowing how the stated one worked. With that point of reference you have no "starting point" to make changes.

 

Hey... They're YOUR chemicals, not mine. Do whatever you want.

 

Lloyd

Edited July 16, 2017 by lloyd

[Bcorso85]

From my own experience, the coarseness of the Mg/Al has the most effect on timing of all the variables, but I make crackle with -200Mg/Al of which each grain explodes only once, loudly. I control the delay-to-burst by varying the prime layer's thickness. The difference, I think, is that mine also includes fine spheroidal aluminum, and I try to control the particle density and particle sizes well.

 

It makes a difference in timing how porous and/or irregular the grains are. I try to keep the porosity low and the shape roughly spherical by gently 'hand rolling' the bits through the sizing screen in the last sizing pass. Whatever gets crushed by that method can simply be re-wet with acetone, and processed again.

 

Material grams

Bismuth Trioxide 71.2

MgAl 200m 14.4

Black Copper Oxide 9.4

Atom. Alum 12 micron 5.0

100.0

 

Use no less than 2.65% (up to about 3%) of the dry mixture's weight in double-based powder for the NC binder, dissolved in 'enough' acetone to make it a pourable consistency. I use about 1 part powder to 8.5-9 parts acetone. (w/v, for instance, 60g in 500ml)

 

This will make an almost 'batter-like' mixture. Make sure to use ALL of the NC mixture per batch. For instance, at that concentration, I use 60g of Green Dot in 500ml acetone for each 5lb of dry power mixture -- and ALL of it!

 

Continue to stir and mix the mass until it becomes a stiff-enough 'dough' to begin screening 'worms' for final sizing.

 

-8+10mesh particles for 22-30mm comets, -6+8 for 38-45 mm comets.

Also -6+8 for small 'crackle-only' mines or crackling pistils.

 

Roller-prime with 'rough powder' mixture with +6% dextrin, using potassium dichromate saturated-solution for the wetting water.

 

'Hope that helps.

Lloyd

Hey Lloyd,

I am a bit new to DE and have a few questions for you.

 

1) What's the function of the Atomized Aluminum? If necessary will Alcoa 180 work in a bind, or ruin the effect/volume?

 

2) A 100Gram batch of DE should have how much dry double based NC measured out? 10 Grams?

 

3) I substituted 9% -60 Ferro Alum for TI. Will the aluminum have an adverse effect, or no because it is a larger particle?

 

Thanks in advance,

Ben

[RichardH08]

Having played with a lot of different crackle compositions, I think I can answer most of these questions.

 

Firstly, it might be worth pointing out that the formula Lloyd gives here is different from the one listed in his article in Fireworking.com, which reverses the amounts of CuO and MgAl. I've only tried it with 14% CuO and 10% MgAl so I can't entirely vouch for how this one works. But I get the impression that this type of crackle isn't particularly sensitive to modest changes in the proportions.

 

1) In most crackle compositions I've come across, including some atomized Aluminum makes the sound louder and sharper, sometimes at the expense of increasing the delay from ignition to explosion. In my experience flake aluminum doesn't have the same effect, possibly because it is too reactive.

 

2) Lloyd recommends 2.5 to 3% of dry NC (double based or not) so, for a 100 gram batch you need 2.5 to 3 grams. In my experience anything in that range works fine. More is probably OK, but not necessary. If you use less, the grains tend to make multiple crackles rather than a single loud report.

 

3) I'm not sure what this question means. Are you saying you substituted FerroAluminum for the Aluminum? If so, then you are making a significant change to the chemistry and I have no idea what the effect might be.

[Bcorso85]

Hey Richard,

I substituted Ferro Aluminum for Ferro Titanium. My Titanium is either too small or too big for the crackle formula. I misunderstood the 10% NC, and made a slurry of 10 grams of NC and added it to 100G batch slowly. Previous comments above aside, instead of 200M atomized Aluminum I used 180M Atomized Alcoa.

I ran then through an 8 mesh screen, and have nice tiny star cores unprimed. They crackle, they're gold, and they ignite from a visco fuse. Unprimed they just aren't LOUD. From what I've read priming them will help the volume. But my gut tells me it wont be as loud as I want.

 

I took the dry mix, the tip of a spoon full, and lit it. It was like a 9MM. But when I add the NC, it seems the formula cools off. This is why I think I must be doing something wrong. I don't think it's the Ferro Aluminum instead of Ferro Titanium.

[RichardH08]

Hi Ben,

 

When making that crackle I use -350 mesh atomized aluminum, which is close to what is usually recommended. As far as I know, using something a bit coarser, such as 180 mesh, ought to still work but might well make a difference to the performance. I don't really know for certain, as that is something I haven't tried.

 

I'm also not sure what using more than the recommended amount of NC will do. For many crackles the authors say something like 'the more NC the better' but that might not be the case with this one.

 

I assume you are adding FeAl (or FeTi) in order to get a spray of sparks as well as the noise. I know that adding too much does reduce the loudness significantly - a very small percentage is all you can get away with. I think 9% might well be over the limit. Apart from that, I doubt your substitution will make that much difference.

 

I hope that helps.

[RichardH08]

In the interests of science, I've decided to run some quick tests on the effects of using a coarser atomized Al and of 'reversing' the proportions of CuO and MgAl. I'll report back when I have some answers.

[dave321]

certainly using conventional crackle formula, too much fine powder Ti can completely kill the noise and actually reduce it completely.

[Mumbles]

This might be total BS. There are some people who believe that the product being made in south-east Asia might not be using the 50:50 MgAl we have most commonly available in the US and Europe. Thus the addition of powdered Al to "adjust" the ratio. I don't know if it's true or not, but that's the explanation I got once when I asked.

 

Ben, I would try to get them working normally first before trying to add sparks. It is easier to troubleshoot issues that way. This is a rather complex reaction as it turns out, and there are a lot of little intricacies to getting them working just right without tossing in extra components and complicating things.

[RichardH08]

I have to concur with Mumbles about it being sensible to start with a standard composition before trying to make changes. It's what I always do. I can't confirm or deny what he says about Asian manufacturers using different proportions in their MgAl, but I do know that the vast majority of their crackle products use formulations that are very different from the one we are discussing here.

 

In my experience, experiments in pyrotechnics never seem to give as clear answers as I would like. Perhaps that’s inevitable. Anyway, here’s what I did, and what I found.

My trial was based around three variants of the crackle composition listed earlier in this thread.

 

Variant A is what I consider to be a ‘standard’ formulation, with 71% Bi₂O₃, 14% CuO, 10% MgAl (-250#) and 5% Al (atomized, -350#), with an additional 2.5% (dry weight) NC dissolved in acetone. Variant B uses a much coarser (100#) atomized aluminium, variant C exchanges the proportions of the CuO and MgAl, and variant D makes both changes. In each case I screen sliced the mixture through an 8-mesh screen and, when dry, lightly coated the grains with rough mix BP containing an additional 4% dextrin.

 

I have made variant A many times and have always found it to perform well, with a delay of less than a second and a single, very loud report. My results indicate that all three of the other variants perform less well; all having a tendency to create multiple crackles, rather than a single explosion. Contrary to what I was expecting, in comparison with variant A, they all had a shorter delay – of around 0.4 to 0.5s – to the first report.

 

I didn’t see a huge difference in performance between any of the three, but if I had to put them in order, from best to worst in terms of the number of reports each produced (more being worse) it would be: C, B, D.

 

Interestingly, that also appears to be the order of decreasing delay. Perhaps that isn’t so surprising, as a grain that crackles is probably heating up more unevenly than one that produces just one report. If that is the case, it would be reasonable for some small portion to react more quickly than the average for a whole grain.

Edited September 6, 2017 by RichardH08

[Yus]

Who knows new chinese crackling core formula without lead, copper, bismuth, Na2S2O3, Mg, AlMg chemicals?

[OldMarine]

Who knows new chinese crackling core formula without lead, copper, bismuth, Na2S2O3, Mg, AlMg chemicals?

If Richard who posted above you doesn't know I suspect no one does.

[RichardH08]

I don't know of any crackle composition that excludes everything on that list. I analyzed a Chinese sample a couple of years ago and found it to contain copper (II) oxide, aluminum, magnesium (presumably alloyed with part or all of the Al) and a well-cured resin binder. I've made something similar, but it is quite sensitive to the grain size and noticeably harder to ignite than some of the more conventional compositions. Ignition gets more difficult as you reduce the amount of MgAl alloy.

 

I've never got anything to work that doesn't contain both copper oxide and aluminum. I've seen a Chinese patent that suggests the oxides of tin and manganese can be added but, as usual, the description is so vague that it isn't much help. I experimented with them a bit, but the results weren't good.

[Yus]

I've found interesting information about variation of crackling core in AFN II, page 84:

 

"Pyros who are skilled at making round stars in a pan might like to try their hand at making crackle stars. Crackle stars are similar to other round stars except they have an exploding core."

 

"The stars in use in commercial shells are made exclusively in the Orient. The exploding cores are made from a mixture of potassium chlorate and realgar (As2S2). The manufacturing process is described in Fireworks, the Art, Science and Technique by Takeo Shimizu. Experienced pyros realize that realgar is not only poisonous and difficult to obtain, but the realgar-chlorate mixture is extremely sensitive and dangerous to work with. In fact, I was told that crackle stars are no longer made in Japan for that reason. A safer and simpler procedure for making these stars was described in PGI Bulletin # 15 (Japanese Crackle Shell). The author suggested the use of percussion caps available at gun shops for star cores. I have found percussion caps to be expensive and difficult to roll composition on. In their place I have been using pistol primers which are cheaper and have a more rounded shape, and are easier to roll in the pan."

[pirotek]

with the same result, initiating explosives can be used